The present invention generally relates to a carrying device for carrying a substrate to be processed (such as, e.g., a semiconductor wafer). More particularly, the invention relates to a carrying device suitable for transferring the substrate to be processed into and from a substrate processing apparatus equipped with one or more processing chambers for subjecting the substrate to various processings.
Carrying devices have been proposed for transferring substrates into and from processing chambers to perform various processings in a substrate processing apparatus (such as, a semiconductor producing apparatus).
Conventionally, an example of a known carrying device is as shown in Japanese Patent No. 2,531,261.
FIG. 33 is a plan view showing a schematic configuration of a conventional carrying device.
As shown in FIG. 33, in this carrying device 50, first and second parallel link mechanisms 50A, 50B are connected, sharing a link 51.
The first parallel link mechanism 50A is formed by links 51, 52, 53 and 54, while the second parallel link mechanism is formed by links 51, 55, 56 and 57.
Here, the effective lengths of the links 51, 52 and 55 are the same, and those of the links 53, 54, 56 and 57 are the same.
Both ends of each of the links 53, 54, 56 and 57 are rotatably connected. Meanwhile, a gear 63 is fixed to one end of the link 53 on a side of the link 51; a gear 64 is fixed to one end of the link 57 on the side of the link 51; and the gears 63 and 64 have the same diameter and mesh with each other.
In the conventional carrying device 50 having such a configuration, when a drive shaft 62 of a motor 61 fixed to the link 53 is rotated, the link 53 is rotated and the gear 63 is rotated together with the link 53.
In this case, since the links 51 and 52 are kept parallel by the first parallel link mechanism 50A, the gear 63 is rotated at an angular velocity as high as that of the drive shaft 62 with respect to the link 51. And, when the gear 63 is rotated, the gear 64 meshing with it is rotated at the same angular velocity in a reverse direction, so that the link 57 belonging to the second parallel link mechanism 50B is rotated together. As a result, a carrying table 58, which is fixed to the link 55 belonging to the second parallel link mechanism 50B, reciprocally moves linearly.
However, in such a conventional technique, since the gear 63 fixed to one end of the link 53 on the side of the link 51 meshes with the gear 64 fixed to one end of the link 57 on the side of the link 51; the gear 63 and the gear 64 rub against each other at the meshing portions; and dust (such as, metal dust) is formed therefrom. Then, this dust contaminates an object to be carried (not shown), such as a semiconductor wafer or the like, placed on the carrying table 58.
Further, in the conventional technique, the meshing portions of the gears 63 and 64 rub against each other to abrade the gear teeth, and a backlash gets larger in the meshing portions, so that the power of the first parallel link mechanism 50A is not correctly transmitted to the second parallel link mechanism 50B, and the object to be carried cannot be carried to a correct position. This problem is disclosed in Japanese Patent No. 2,531,261.
The present invention has been made to solve the problems of such a conventional technique, and its object is to provide a carrying device that does not produce any dust (such as, metal dust) and can prevent the contamination of an object to be carried (such as, a semiconductor wafer or the like) supported on a carrying table.
Further, another object of the present invention is to provide a carrying device that can rightly transmit the power of a first parallel link mechanism to a second parallel link mechanism and carry an object to be carried, to a correct position, without abrasion at sliding portions.